92 NATURAL SELECTION. Chap. IV. 



effected by glands at the base of the stipules in some 

 Leguminosse, and at the back of the leaf of the common 

 laurel. This juice, though small in quantity, is greedily 

 sought by insects. Let us now suppose a little sweet 

 juice or nectar to be excreted by the inner bases of the 

 petals of a flower. In this case insects in seeking the 

 nectar would get dusted with pollen, and would certainly 

 often transport the pollen from one flower to the stigma 

 of another flower. The flowers of two distinct individuals 

 of the same species would thus get crossed ; and the act 

 of crossing, we have good reason to believe (as will 

 hereafter be more fully alluded to), would produce very 

 vigorous seedlings, which consequently would have the 

 best chance of flourishing and surviving. Some of these 

 seedlings would probably inherit the nectar-excreting 

 power. Those individual flowers which had the largest 

 glands or nectaries, and which excreted most nectar, 

 would be oftenest visited by insects, and would be 

 oftenest crossed ; and so in the long-run would gain 

 the upper hand. Those flowers, also, which had their 

 stamens and pistils placed, in relation to the size and 

 habits of the particular insects which visited them, so as 

 to favour in any degree the transportal of their pollen 

 from flower to flower, would likewise be favoured or se- 

 lected. We might have taken the case of insects 

 visiting flowers for the sake of collecting pollen instead 

 of nectar ; and as pollen is formed for the sole object 

 of fertilisation, its destruction appears a simple loss to 

 the plant ; yet if a little pollen were carried, at first 

 occasionally and then habitually, by the pollen-devour- 

 ing insects from flower to flower, and a cross thus 

 effected, although nine-tenths of the pollen were de- 

 stroyed, it might still be a great gain to the plant ; and 

 those individuals which produced more and more pollen, 

 and had larger and larger anthers, would be selected. 



